Polycyclic aromatic hydrocarbons in sediments from the Old Yellow River Estuary, China: Occurrence, sources, characterization and correlation with the relocation history of the Yellow River

• This is the first study concentrating specifically on PAHs in the Old Yellow River.
• A historical record of PAH contamination was reconstructed in this region.
• Relocation of the Yellow River in 1976 caused further rises in PAHs.
• Relocation of the Yellow River in 1996 caused decrease of PAHs in the mid-1990s.

The levels of 16 USEPA priority PAHs were determined in surface sediments and one dated sediment core from the abandoned Old Yellow River Estuary, China. Total PAH concentrations in the surface sediments ranged from 100.4 to 197.3 ng g−1 dry weight and the total toxic equivalent quantity (TEQcarc) values of the carcinogenic PAHs were very low. An evaluation of PAH sources based on diagnostic ratios and principal component analysis suggested that PAHs in the surface sediments mainly derived from combustion sources. The total PAH concentrations altered significantly with year of deposition and showed quite different patterns of change compared with other studies: it is hypothesized that the principal cause of these changes is the relocation of the course of the Yellow River to the sea in 1976 and 1996.